1. Technical Field
This disclosure relates generally to liquid ejecting apparatuses and methods, and more specifically, to a liquid ejecting apparatus and method capable of recording a relatively high resolution image.
2. Discussion of Related Art
Liquid ejecting apparatuses include apparatuses for recording information by ejecting ink, such as a printer, a plotter, a copying machine, a facsimile machine, and a multi-function device thereof. Liquid ejecting apparatuses also include apparatuses for recording information by ejecting a liquid other than ink, such as a reagent, a DNA sample, and a resist pattern material.
For such liquid ejecting apparatuses, various methods of recording information, such as using images, characters, and patterns, have been proposed. In particular, because of its simple mechanics and advantages it provides in the size and cost reduction, an inkjet recording method is widely used in liquid ejecting apparatuses, for example inkjet printers and inkjet plotters. In the inkjet recording method, a recording head of a liquid ejecting apparatus ejects ink droplets onto a recording medium while scanning the recording medium.
Such inkjet recording method has been used to print a color photographic image, enhancing the resolution of the image thus obtained. Further, the inkjet recording method is used to record or produce an electronic circuit or a liquid crystal panel. In this case, the liquid ejecting apparatus ejects liquid polymer, instead of ink, onto an electronic circuit or a liquid crystal panel.
A liquid ejecting apparatus employing such inkjet recording method (hereinafter, an inkjet recording apparatus) typically records an image on a recording medium as follows: First, an inkjet recording apparatus applies pressure to the ink accommodated in an ink chamber of a recording head by vibration or thermal expansion of a piezoelectric element. Then, through ejection nozzles, the recording head ejects the ink as droplets onto the recording medium. Thus, the ink droplets on the recording medium may form a dot pattern to record a desired image.
An example of such an inkjet recording apparatus is an inkjet recording apparatus of a serial scan type. An inkjet recording apparatus of this type is provided with a recording head including a plurality of ink ejection nozzles. In the recording head, the plurality of nozzles is arranged in a sub-scanning direction, that is, a direction in which a recording medium is conveyed. The serial-scan inkjet recording apparatus ejects ink droplets through the nozzles onto the recording medium while moving the recording head in a main scanning direction perpendicular to the sub-scanning direction.
While moving the recording head from one end to the other end in the main scanning direction, the serial-scan inkjet recording apparatus records an image having a length corresponding to that of the recording head in the sub-scanning direction. After the recording medium is fed by a certain amount (e.g. one line image), the serial-scan inkjet recording apparatus records an image of another line on the recording medium in a manner similar to that described above.
Another example of an inkjet recording apparatus is a line-type inkjet recording apparatus. A line-type inkjet recording apparatus includes a line-type recording head. The line-type recording head has a length corresponding to a full length of a main scanning area thereof. While feeding a recording medium in the main scanning direction, the line-type inkjet recording apparatus ejects ink droplets from the line-type recording head onto the recording medium to form a desired image.
For such inkjet recording apparatuses, a high quality image may be obtained by increasing the resolution of the image. In general, the resolution of an image is expressed in units of dots-per-inch (dpi). Dpi indicates the number of ink droplets per inch, ejected onto a recording medium. The larger the dpi value, the higher the resolution of the image.
For example, to obtain an image with a resolution of 600 dpi, a recording head having 600 nozzles per inch is typically needed. Further, to obtain an image with a higher resolution, the number of nozzles arrayed per inch in the recording head should be increased. Furthermore, such increase of the number of nozzles may necessitate a change in configuration of the ink chamber or an ink supply passage.
Such an increase in the number of nozzles per inch of a recording head is first considered as a way to obtain a high resolution image with an inkjet recording apparatus. Such an increase in the number of nozzles may be achieved by reducing the internal diameter of each nozzle. However, there is a limit to such reduction of the internal diameter of the nozzle due to technical constraints in manufacturing the nozzle. Further, even if the internal diameter of the nozzle is reduced to a certain size, the nozzle might get clogged during an image recording operation by paper dust, for example.
Alternatively, when the nozzle size is reduced, ink chambers communicating with respective nozzles and piezoelectric elements mounted thereon may also need to be arranged at relatively high density. Such high-density arrangement may be difficult to achieve due to constraints imposed by the size of the recording head and/or technical limitations in fabricating a nozzle or ink chamber. Further, use of such fine processing technologies may cause a reduction of yield in manufacturing.